JP2007074218A - Program, device, and method for controlling packet transmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technique capable of performing communication in which the dead line of a packet is insured in an entire network. <P>SOLUTION: A packet scheduler, which controls the transmission sequence of a periodical communication task, is provided in an information processor. A usable communication band is given to the information processor. When a utilization band does not exceed the usable communication band, and a dead line monotonic method determines that the dead line can be insured; the packet scheduler registers a requested communication task as a communication task to be executed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a packet transmission control program, a packet transmission control device, and a packet transmission control method.

Conventionally, EDF (Earliest) is considered for deadline in real-time packet communication.
A technique for performing packet communication based on a (Deadline First) algorithm is known (Patent Documents 1 and 2).

The EDF algorithm is an algorithm that preferentially executes a process with the closest deadline.
Special Table 2002-543520 Japanese translation of PCT publication No. 2003-505931

  However, in the EDF method that preferentially executes the process with the closest deadline, packets with a short deadline are frequently transmitted depending on the generation timing of the packet transmission request. The line may not be guaranteed.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a technique for guaranteeing a deadline of packet transmission in an information processing apparatus connected to a network.

  In order to achieve the above object, in the present invention, packet communication in which a deadline is guaranteed is performed by the following means or processing.

  The packet transmission control program according to the present invention is a packet transmission control program for controlling packet transmission in an information processing apparatus connected to a network. The packet transmission control program according to the present invention causes the information processing apparatus to function as a transmission request reception unit, a schedulability determination unit, and a packet control unit.

  The transmission request accepting unit accepts a periodic packet transmission execution request in which a deadline is determined in each cycle.

  The schedulability determining means determines whether or not the requested packet transmission deadline can be guaranteed, and if the deadline can be guaranteed, registers the requested packet transmission as a communication task to be executed.

  The packet control means transmits the packet of the registered communication task with a priority according to the deadline of the communication task.

The schedulability determination means can guarantee a deadline for all already registered communication tasks and requested packet communications, and the unit per unit time when a packet is transmitted so as to guarantee all deadlines. When the packet transfer amount (data transfer amount) is within a predetermined maximum transfer amount given to the information processing apparatus, the requested packet transmission is registered as a communication task to be executed.

  As described above, the packet transmission control program according to the present invention determines whether or not the packet transmission deadline can be guaranteed in each information processing apparatus, and further, the maximum transfer to which the packet transfer amount of each information processing apparatus is allocated. Since it is determined whether or not the packet transmission request is to be registered after determining whether or not the amount is within the amount, it is possible to guarantee a deadline of packet transmission for all information processing apparatuses in the network.

The schedulability determination means in the present invention is a deadline monotonic (Deadline monotonic).
According to the Monotonic method, it is preferable to determine whether deadline guarantee is possible for all already registered communication tasks and requested packet transmissions.

  More specifically, the packet transmission request accepted by the transmission request accepting unit preferably includes, as information, a transmission cycle of packet transmission, a transmission data amount per cycle, and a deadline in each cycle. Here, the deadline in each cycle is the same time as the transmission cycle or shorter than the transmission cycle.

  First, the schedulability determining means calculates the required transmission time required for packet transmission from the amount of transmission data per cycle and the effective communication speed of the network. Next, the schedulability determining means determines schedulability by the deadline monotonic method using the transmission cycle, the calculated required transmission time, and the deadline.

  Note that the schedulability determination means does not need to determine whether the transmission cycle, the transmission required time, and the deadline satisfy the necessary and sufficient conditions for guaranteeing the deadline, but the sufficient conditions for ensuring the deadline. Only whether or not the above condition is satisfied may be determined. In the deadline monotonic method, determination of necessary and sufficient conditions is complicated and requires time for processing. Therefore, it is also preferable to use determination under sufficient conditions of light processing.

  The predetermined maximum transfer amount allocated to the information processing apparatus provided with the packet transmission control program according to the present invention is given in advance to the information processing apparatus as setting information, or is given from the total transmission amount management server of each information processing apparatus. It is preferable that

  In addition, the maximum transfer amount does not always have to be the same value, and the packet transmission control program is a unit in which a packet is transmitted so as to guarantee a deadline for all registered communication tasks and requested packet transmissions. When the transfer amount per time exceeds the maximum transfer amount, it is preferable to ask the overall transmission amount management server to increase the maximum transfer amount.

  The present invention can be understood as a packet transmission control program having at least a part of the above processing. Further, the present invention can be understood as a packet transmission control device including at least a part of the above means or a packet transmission control method including at least a part of the above processing. Each of the above means and processes can be combined with each other as much as possible to constitute the present invention.

For example, a packet transmission control apparatus as one aspect of the present invention is a packet transmission control apparatus that controls packet transmission in an information processing apparatus connected to a network, and is a periodic transmission in which a deadline is defined in each period. A transmission request receiving means for receiving an execution request for packet transmission, and determining whether or not the requested packet transmission deadline can be guaranteed. If the deadline can be guaranteed, the requested packet transmission is executed. Schedulability determination means for registering as a communication task; and packet control means for transmitting a packet of the registered communication task with a priority according to a deadline of the communication task, and determining the schedulability Means dead for all already registered communication tasks and the requested packet transmission. The requested packet transmission is executed when the transfer amount per unit time when the packet is transmitted so as to guarantee all deadlines is within a predetermined maximum transfer amount. It is registered as a communication task.

  A packet transmission control method according to an aspect of the present invention is a packet transmission control method for controlling packet transmission in an information processing apparatus connected to a network, wherein the information processing apparatus performs deadline in each cycle. Can accept a periodic packet transmission execution request, can guarantee a deadline for all of the already registered communication tasks and the requested packet transmission, and When the transfer amount per unit time when transmitted is within a predetermined maximum transfer amount, the requested packet transmission is registered as a communication task to be executed, and the packet of the registered communication task is registered in the communication It transmits with the priority according to the deadline of a task.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to guarantee the deadline of the packet transmission in the information processing apparatus connected to the network.

  Exemplary embodiments of the present invention will be described in detail below with reference to the drawings.

[First Embodiment]
<System overview>
FIG. 1 is a diagram illustrating a network system of an information processing apparatus that executes a packet scheduler (packet transmission control program) according to the present embodiment. A plurality of information processing apparatuses 1a, 1b, and 1c are connected via the network 3, and each information processing apparatus performs packet communication with each other. Here, the information processing apparatus 1c also functions as an overall transmission amount management server that manages the maximum amount of packets that can be transmitted per unit time by each of the information processing apparatuses 1a, 1b, and 1c.

  FIG. 2 is a diagram illustrating a configuration of the information processing apparatus 1 that executes the packet scheduler. The information processing apparatus 1 includes a CPU 11, a timer 12, an auxiliary storage device 13 such as a hard disk device, a memory 14 such as a readable / writable memory (RAM), and a network control unit 15. Each of these elements is connected to each other via a bus.

  The timer 12 records the current time (system time) in the information processing apparatus 1. The packet scheduler controls packet transmission based on the system time of the timer 12.

  The auxiliary storage device 13 stores a packet scheduler and other application programs. These software are appropriately read from the auxiliary storage device 13 to the memory 14 as necessary, and are executed by the CPU 11. The memory 14 stores information on communication tasks managed by the packet scheduler (period, data transfer amount, deadline, priority, etc.) and the maximum transfer amount that the information processing apparatus 1 can transmit (send) per unit time. Etc. are memorized.

The information processing apparatus 1 is connected to the network 3 via the network control unit 15.

  As described above, the information processing apparatus 1c in FIG. 1 also functions as an overall transmission amount management server. The total transmission amount management server has a function of determining the maximum transfer amount that each information processing apparatus connected to the network 3 can transmit per unit time. In this way, the overall transmission amount management server determines the maximum transfer amount of each information processing apparatus, thereby preventing excessive communication from occurring in the entire network.

<Functional configuration>
FIG. 3 is a functional block diagram of the information processing apparatus 1 that executes the packet scheduler. The function of the packet scheduler includes a transmission request receiving unit 21, a maximum transfer amount acquisition unit 22, a communication speed acquisition unit 26, a schedule possibility determination unit 23, and a packet control unit 25. The functions of these units are realized by the packet transmission control program being executed by the CPU 11.

  The transmission request receiving unit 21 receives a packet transmission request from the application program 4. Since the packet scheduler is a program that functions on the IP (Internet Protocol) layer, a transport such as TCP (Transmission Control Protocol) or UDP (User Datagram Protocol) is provided between the application program 4 and the transmission request receiving unit 21. Layers and application layers thereabove exist, and a program that implements these protocol layers mediates, but is omitted in FIG.

  The packet transmission request received by the transmission request receiving unit 21 needs to transmit a predetermined amount of data at regular intervals, and needs to complete packet transmission within a predetermined time (deadline) from the start of transmission.

  FIG. 4 is a diagram for explaining a communication task for periodic packet transmission. As shown in FIG. 4A, it is necessary to transmit a predetermined amount of packets every fixed period T. Also, a deadline D that is a time limit for completing this transmission is defined. Note that if the transmission of the packet is completed within the deadline, it is considered that the packet has been correctly processed. Therefore, as shown in FIG. 4B, in a situation where there are a plurality of communication tasks, it is not necessary for each communication task to transmit all the data continuously within one period, but to transmit in a divided manner. It does not matter if it becomes.

  The maximum transfer amount acquisition unit 22 acquires the maximum transfer amount that is the maximum amount that the information processing apparatus 1 is permitted to transmit per unit time from the total transmission amount management server. As described above, the total transmission amount management server determines the maximum transfer amount of each information processing apparatus. In the present embodiment, the maximum transfer amount is notified from the overall transmission amount management server to the information processing apparatus 1 by communication.

  The communication speed acquisition unit 26 acquires the effective communication speed of the network 3. The effective communication speed may be acquired by actual measurement, or a predetermined setting value may be used.

  The schedulability determination unit 23 determines whether or not the packet transmission request received by the transmission request reception unit 21 can be transmitted while keeping the deadline. If deadline guarantee is possible, it is registered in the communication task management table 24 as a communication task to be executed. Details of the function of the schedulability determination unit 23 will be described later.

The packet control unit 25 performs packet transmission based on information stored in the communication task management table 24. The packet transmission communication task has a higher priority as the deadline is shorter, and the packet control unit 25 selects a packet to be transmitted based on this priority.

<Processing flow>
(Schedulability determination process)
Next, the schedule possibility determination process performed by the schedule possibility determination unit 23 will be described with reference to FIG.

  First, in step S101, the schedulability determination unit 23 sums up the packet transmission received by the transmission request reception unit 21 and the tasks stored in the communication task management table 24 as communication tasks already executed. Calculate the amount of data transferred per hour. This can be obtained by Σ (transmission data amount / cycle of each transmission). Note that (transmission data amount) / (cycle) is rounded up in units of MTU (Maximum Transfer Unit).

  Next, in step S102, it is determined whether the calculated data transfer amount per unit time is within the maximum transfer amount acquired by the maximum transfer amount acquisition unit 22. Here, when the calculated data transfer amount is a transfer amount exceeding the maximum transfer amount, the process proceeds to step S106, and the execution is rejected without registering the received packet transmission. If the calculated data transfer amount is within the maximum transfer amount, the process proceeds to step S103.

  In step S103, a transmission required time required for one cycle transmission of the requested packet transmission is calculated. The required transmission time can be obtained by dividing the data transfer amount per cycle by the communication speed of the network 3 acquired by the communication speed acquisition unit 26. (Time required for transmission) = (data transfer amount per cycle) / (network communication speed). Note that the data transfer amount per cycle is rounded up and used in units of MTU.

  In step S104, the schedulability determining unit 23 uses the deadline monotonic method to determine whether the deadline can be guaranteed for the already registered communication task and the requested packet transmission.

  In the deadline monotonic method, the cycle of each packet transmission, the time required for transmission per cycle, and the deadline are used. Any known method may be used as a determination method for determining schedulability based on such information. For example, a judgment formula that is a necessary and sufficient condition for scheduling possibility may be used, or a sufficient condition may be used.

なお、Ｔｉ，Ｃｉ，Ｄｉは、それぞれ通信タスクｉの周期、送信所要時間、デッドラインである。また、通信タスクｉは、ｉ＝１の通信タスクが最も優先度が高く、ｉが大きくなるにしたがって優先度が小さくなる。
また、

は、ｘ以上の最小整数を表す。 For example, the following determination formula can be used as a determination formula that represents a sufficient condition for scheduling possibility.

Ti, Ci, and Di are the communication task i period, transmission time, and deadline, respectively. The communication task i has the highest priority for the communication task with i = 1, and the priority decreases as i increases.
Also,

Represents the smallest integer greater than or equal to x.

  Other judgment formulas are described in the following documents, for example.

  Audsley, Burns, Richardson, Wellings, "Hard Real-Time Scheduling: The Deadline-Monotonic Approach", Proceedings of the 8th IEEE Workshop on Real-Time Operating Systems and Software, 1991

  When the possibility of scheduling is determined according to such a determination formula and the deadline can be observed for all of the already registered communication tasks and the requested communication tasks, the process proceeds to step S105 and the requested The packet transmission is stored in the communication task management table 24 as a communication task to be executed. If the deadline cannot be guaranteed, the process proceeds to step S106, and the received packet transmission is not registered and its execution is rejected.

(Packet transmission processing)
Next, packet transmission processing performed by the packet control unit 25 will be described with reference to FIG. The packet control unit 25 controls the packet transmission order based on information such as the period and deadline stored in the communication task management table 24.

  In step S201, the packet control unit 25 refers to the communication task management table 24 and selects a communication task having the highest priority and having not completed packet transmission. As described above, the priority of the communication task is set higher as the deadline is shorter.

  Next, in step S202, the packet control unit 25 transmits a packet of the selected communication task for 1 MTU. After the transmission for 1 MTU, the process returns to step S201 again.

(Effect of embodiment)
In the present embodiment, the amount of data transmitted by each information processing apparatus is managed by the total transmission amount management server. Furthermore, each information processing apparatus accepts only a communication task that is guaranteed to complete communication within the deadline by the deadline monotonic method within the range of available transfer amount. Therefore, the entire network system can transmit packets while keeping the deadline.

[Second Embodiment]
The second embodiment is different from the first embodiment only in the process (see FIG. 5) performed by the schedule possibility determination unit 23, and the other parts are the same as those in the first embodiment. .

  FIG. 7 is a flowchart showing the schedulability determination process of the schedulability determination unit 23 in the second embodiment. Of the processing in FIG. 7, portions different from the first embodiment will be described in detail.

As in the first embodiment, in step S302, the data transfer amount per unit time required when the requested packet transmission and the already registered communication tasks are added is allocated to the information processing apparatus 1. Judge whether it is within the maximum transfer amount. If the required data transfer amount per unit time exceeds the maximum transfer amount, the process proceeds to step S303.

  In step S303, the maximum transfer amount acquisition unit 22 requests the overall transmission amount management server to increase the maximum transfer amount. Here, the newly requested maximum transfer amount is not less than the required data transfer amount per unit time obtained in step S302. In step S304, it is determined whether a request to the total transmission amount management server has been approved. If the request is accepted, the process proceeds to step S305, and the scheduling possibility determination by the deadline monotonic method is performed. If the request is not accepted, the process proceeds to step S308, and the requested packet transmission is rejected.

  The total transmission amount management server manages the amount of data that can be transmitted per unit time (available bandwidth) in the entire network and the maximum amount of transmission data that each information processing device transmits per unit time. If there is a margin, the request for increasing the maximum transfer amount from the information processing apparatus 1 can be accepted.

  As described above, in the second embodiment, the amount of data that each information processing apparatus can transmit per unit time can be increased as necessary, so that more flexible scheduling is possible.

  When the increase in the maximum transfer amount is recognized in this way, when the transfer amount required by the information processing apparatus 1 becomes lower than the maximum transfer amount, a request for reducing the maximum transfer amount is managed as the total transmission amount management. It goes without saying that notification to the server is effective from the viewpoint of effective use of network resources.

[Third Embodiment]
In the third embodiment, the information processing apparatus is connected to a plurality of networks. As shown in FIG. 8, the information processing apparatus 6 is connected to a plurality of networks via a plurality of network control units 15a, 15b, and 15c. In this case, the entire network system including the information processing apparatus 6 is as shown in FIG. In FIG. 9, the information processing apparatus 6 is connected to networks 7a, 7b, and 7c. Examples of the plurality of networks include Ethernet (registered trademark), mobile phone, optical communication, and wireless communication.

  In this case, the information processing apparatus 6 has a communication task management table for each network. The schedulability determination unit 23 performs a schedulability determination process similar to that in the above-described embodiment using a communication task management table corresponding to a transmission destination network, thereby ensuring a deadline in each network. Can be performed.

  In FIG. 9, only one information processing apparatus is connected to a plurality of networks, but it is obvious that there may be a plurality of information processing apparatuses.

[Modification]
In the above embodiment, the maximum value of the data amount that can be transmitted per unit time by the information processing apparatus is acquired from the total transmission amount management server. However, such a configuration is not necessarily required, and the maximum transfer amount may be given in advance to the information processing apparatus as setting information such as a setting file.

1 is a schematic diagram of a network system in which a packet scheduler according to a first embodiment is used. It is a figure which shows the structure of the information processing apparatus which performs the packet scheduler in 1st Embodiment. It is a functional block diagram of the packet scheduler in 1st Embodiment. It is a schematic diagram explaining a periodic task. It is a flowchart which shows the scheduling possibility determination process in 1st Embodiment. It is a figure which shows a process for packet transmission control in 1st Embodiment. It is a flowchart which shows the scheduling possibility determination process in 2nd Embodiment. It is a figure which shows the structure of the information processing apparatus which performs the packet scheduler in 3rd Embodiment. It is a schematic diagram of the network system in which the packet scheduler in 3rd Embodiment is utilized.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Information processing apparatus 2 Packet scheduler 3 Network 4 Application 6 Information processing apparatus 7 Network 11 CPU
DESCRIPTION OF SYMBOLS 12 Timer 13 Auxiliary storage device 14 Memory 15 Network control part 21 Transmission request reception part 22 Maximum transfer amount acquisition part 23 Schedule possibility determination part 24 Communication task management table 25 Packet control part 26 Communication speed acquisition part

Claims (7)

A packet transmission control program for controlling packet transmission in an information processing apparatus connected to a network,
The information processing apparatus;
A transmission request receiving means for receiving a periodic packet transmission execution request with a deadline determined in each cycle;
Determining whether the requested packet transmission deadline guarantee is possible, and if the deadline guarantee is possible, the scheduling possibility judgment means for registering the requested packet transmission as a communication task to be executed;
Function as packet control means for transmitting the packet of the registered communication task with a priority according to the deadline of the communication task;
The schedulability determining means can guarantee a deadline for all of the already registered communication tasks and the requested packet transmission, and per unit time when a packet is transmitted so as to guarantee all the deadlines. A packet transmission control program for registering the requested packet transmission as a communication task to be executed when the transfer amount is within a predetermined maximum transfer amount. The packet transmission execution request includes a transmission cycle, a transmission data amount per cycle, and a deadline in each cycle.
The schedulability determining means calculates a transmission time required for requested packet transmission from the transmission data amount per cycle and the effective communication speed in the network, and the transmission cycle, the transmission time, and the dead The line is used to determine whether the deadline guarantee is possible for all of the already registered communication task and the requested packet transmission by a deadline monotonic method. The packet transmission control program described.   The packet transmission control program according to claim 1, wherein the predetermined maximum transfer amount is given in advance to the information processing apparatus as setting information.   3. The packet transmission control program according to claim 1, wherein the predetermined maximum transfer amount is given from an overall transmission amount management server that manages a transmission amount of the information processing apparatus connected to the network.   When the transfer amount per unit time when the packet is transmitted so as to guarantee the deadline for all of the already registered communication task and the requested packet transmission exceeds the maximum transfer amount, the whole 5. The packet transmission control program according to claim 4, wherein an increase in the predetermined maximum transfer amount is obtained from a transmission amount management server. A packet transmission control device for controlling packet transmission in an information processing device connected to a network,
A transmission request receiving means for receiving a periodic packet transmission execution request with a deadline determined in each cycle;
Determining whether the requested packet transmission deadline guarantee is possible, and if the deadline guarantee is possible, the scheduling possibility judgment means for registering the requested packet transmission as a communication task to be executed;
Packet control means for transmitting the packet of the registered communication task with a priority according to the deadline of the communication task;
Have
The schedulability determining means can guarantee a deadline for all of the already registered communication tasks and the requested packet transmission, and per unit time when a packet is transmitted so as to guarantee all the deadlines. The packet transmission control apparatus, wherein the requested packet transmission is registered as a communication task to be executed when the transfer amount is within a predetermined maximum transfer amount. A packet transmission control method for controlling packet transmission in an information processing apparatus connected to a network,
The information processing apparatus is
Accepts periodic packet transmission execution requests with deadlines defined in each cycle,
A deadline can be guaranteed for all of the communication tasks already registered and the requested packet transmission, and the transfer amount per unit time when a packet is transmitted so as to guarantee all the deadlines is a predetermined maximum transfer. If it is within the amount, register the requested packet transmission as a communication task to be executed,
A packet transmission control method, wherein the packet of the registered communication task is transmitted with a priority according to a deadline of the communication task.

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